What you really need for a first firearm is a good .22 LR Rifle, I prefer a lever-action, but a bolt-action or single-shot will do as well or possibly better.
You need a .22 because there is only one way to become a good marksman, you must fire many thousands of rounds of ammunition in practice. You can purchase 500 rounds of .22 LR ammo for less than the cost of 20 rounds of most rifle cartridges, or 50 rounds of centerfire handgun cartridges. The .22 also has negligible recoil and very mild report, this prevents you from developing a horrible flinch which is very hard and very expensive to cure. In my opinion, and in the opinion of most real expert shooters, the .22 LR is the absolute perfect firearm to use to learn basic gun handling, marksmanship, and safety skills.
Get the .22 rifle and burn up a few thousand rounds, learn to hit what you are shooting at, and then move on to handguns. Again, I suggest your first handgun should be a .22 LR. My preference is for revolvers, such as the S&W M-17, M-617, M-63, or one of the various Taurus M-94's. The reason I suggest a revolver first is that you won't be distracted by the flying brass, and good quality revolvers sell for lower prices than similar quality semi-automatics. If you insist on a semi-auto, Ruger makes a number variations of their fine Mk II and Mk III Standard and Target semi-autos, select the one that best fits your hand and budget. Browning's Buckmark and S&W M-22A pistols would also make good choices.
Spend another year learning to handle a .22 handgun and you will start shooting your first .45 ACP as a pro instead of a tyro.
I've said it many, many times, but I think it bears repeating. In over 40 years of shooting and hanging out with gun cranks, I've never known a good shot who did not start with a .22.
Do yourself a huge favor. Learn the basics with a .22 before you jump off into centerfire handguns.
Doc